Engineering Commons^™

Development Of Satellite-Assisted Forecasting System For Vibrio Vulnificus Prevalence In Coastal Waters, Saber Aradpour

LSU Doctoral Dissertations

Vibrio vulnificus is a halophilic gamma proteobacterium that is autochthonous to coastal waters and is responsible for 50% of seafood-related deaths in the United States. This study presents a series of nowcasting and forecasting models for predicting vibrio vulnificus abundance in oysters by identifying the long-range dependence of vibrio vulnificus abundance on antecedent environmental conditions and detecting the environmental conditions using satellite remote sensing technology. It was discovered that vibrio vulnificus abundance exhibits a long-range dependence on antecedent environmental conditions which can be characterized by seven independent environmental predictors (stressors) including sea surface temperature (SST), water level (WL), sea surface …

Assessment Of Engineering Performance And Environmental Impacts Of High Reclaimed Asphalt Pavement (Rap) Asphalt Mixtures In Flexible Pavements, Ibrahim A.I.E. Elnaml

LSU Doctoral Dissertations

Due to the critical role of asphalt pavements in national infrastructure development, there is a pressing need to investigate more sustainable materials and approaches. The use of natural aggregates and asphalt binders in asphalt pavement presents sustainability challenges due to the depletion of finite resources. Recycling Asphalt Pavement (RAP) offers a promising sustainable solution by substituting virgin aggregates and asphalt binders with recycled ones. However, increasing RAP contents in asphalt mixtures (>25%) can lead to premature cracking, insufficient durability, and limited longevity due to the presence of aged RAP-asphalt binder. To address these concerns, the application of novel recycling …

Size Effects In Additively Manufactured Inconel-718 Thin Elements And Cellular Structures, Reem Abdelkarim Abo Znemah

LSU Doctoral Dissertations

A current focus in the additive manufacturing (AM) research community is the production of complex shaped metallic parts and cellular structures. Many researchers went on analyzing and simulating these structures without considering the effect of the element thickness and heterogeneous printing parameters on the resulting material behavior. To advance the application of laser powder bed fusion (LPBF), an AM process, in producing Inconel718 (IN718) complex shaped parts and cellular structures, this study aimed to investigate the effect of thin-walled elements thickness on the mechanical characteristics of both the individual elements and overall cellular structure. A multiscale experimental evaluation of the …

Physics-Based Crystal Plasticity Model For Predicting Microstructure Evolution And Dislocation Densities, Juyoung Jeong

LSU Doctoral Dissertations

This work presents three different studies investigating plastic deformation mechanisms in metals and alloys using crystal plasticity finite element (CPFE) modeling. The first study presents a new nonlocal crystal plasticity model for face-centered cubic single crystals under heterogeneous inelastic deformation. The model incorporates generalized constitutive relations that incorporate the thermally activated and drag mechanisms to cover different kinetics of viscoplastic flow in metals and describes the plastic flow and yielding of single-crystals using dislocation densities. The model is compared to micropillar compression experiments for copper single crystals and clarifies the complex microstructural evolution of dislocation densities in metals. The second …

Numerical Investigation Of Heat Generation And Accumulation Contributing To Elevated Temperature In Msw Landfills, Alborz Fathinezhad

LSU Doctoral Dissertations

Landfills are complex geostructures which contains organic and inorganic municipal, and in some cases industrial, wastes and are expected to remain operational for long times. Due to the complex nature of physical, chemical, biological, and thermal reactions that carry on within the depths of a landfill, unexpected incidents such as elevated temperatures could become inevitable. While uncommon to happen, elevated temperatures cause health and environmental issues such as odors, rapid settlements, slope instabilities. In addition, elevated temperatures can negatively impact engineered components in composite bottom liners, cover systems, leachate collection, and gas extraction and recovery systems.

Air intrusion into municipal …

Incorporating Geopolymer Binders To Fully Utilize Recycled Concrete Aggregates, Matthew Upshaw

LSU Doctoral Dissertations

This study aims to develop a geopolymer concrete binder that will yield desirable strength and durability characteristics when applied to recycled aggregate concrete. In order to achieve this, a geopolymer binder consisting of a metakaolin-silica fume aluminosilicate source material blend activated by potassium-based alkaline solutions is developed and used in place of ordinary Portland cement (OPC) with four different levels of recycled aggregate replacement ratios. The properties of these concretes were analyzed and compared with the properties of OPC concretes produced with the same replacement ratio levels. The results showed that the geopolymer recycled aggregate concrete (GRAC) achieved greater than …

A New Generation Of Open-Graded Friction Course For Enhanced Durability And Functionality, Hossam Abohamer

LSU Doctoral Dissertations

This study aims at (1) enhancing Open Graded Friction Course (OGFC) mixes durability using additives and other by-products; (2) investigating the impacts of selected factors on OGFC pavements seepage characteristics; (3) developing a quantitative tool to model the deterioration in OGFC pavements functional performance; and (4) developing new guidelines of Air Void (AV) content for OGFC for optimum functionality and durability. For the durability objective, eight mixes were prepared with a PG 76-22 binder and two sources of aggregate (i.e., # 78 limestone and # 67 sandstone). Three Warm Mix Additives (WMA), one by-product (i.e., crumb rubber [CR]), and two …

Investigation Of Groundwater Depletion And Leveel Underseepage With Unstructured-Grid Modeling Approach, Ye-Hong Chen

LSU Doctoral Dissertations

Unstructured grid is a tessellation of geometric shapes in irregular patterns that provides flexibility in grid design for groundwater modeling. However, groundwater modeling is mostly developed with uniform grid tessellation and layer, which could simplify model structure or cause expensive computational costs in high-resolution simulations. Unstructured grid incorporates non-uniform horizontal and non-uniform vertical discretizations providing the capability to replicate complex hydrostratigraphy, capture geologic features that are crucial for groundwater flow simulation, and reduce computational costs while maintaining a high resolution for areas of interest. This study contains three parts to investigate unstructured-grid approach on constructing high-fidelity groundwater models, comparisons with …

Engineered Cementitious Composite For Pavement Applications: Materials Development And Design Framework, Hassan Noorvand

LSU Doctoral Dissertations

Engineered Cementitious Composites (ECCs) are a novel class of high-performance fiber-reinforced cementitious composites characterized by their high tensile strain capacity. While ECCs have been presented as a promising material alternative for the construction of durable pavements and overlays, the cost of these materials is a major drawback, which limits their widespread implementation. More importantly, performance prediction models for ECC pavements existing in the literature are incomplete as the effect of ECC plasticity has not been considered in the integration of finite element (FE) analysis and beam flexural fatigue experimental test results. Moreover, the existing ECC pavements performance prediction models are …

An Improved Earned Value Management Method Integrating Quality And Safety, Brian Briggs

LSU Doctoral Dissertations

The construction industry invests significant time and money to improve quality and safety while reducing cost and schedule impacts. The industry has a sincere desire to improve construction project management methods to improve efficiency. Historically, quality and safety underperformances result from undermanaged quality control and safety activities. The cost and schedule impacts associated with poor quality work have always had an impact on construction operations. The unprecedented challenges and uncertainties of COVID-19 highlighted the need to improve the Earned Value Management (EVM) method within construction to reflect these quality and safety activities. The central goal of this dissertation is to …

Vertical Feature Delineation For Flood Hazard Assessments At The Coastal Land Margin, Shu Gao

LSU Doctoral Dissertations

Coastal and riverine flooding constitutes a major environmental hazard that affect millions of people residing along the world’s coastline. Improved understanding of the driving mechanisms that can cause flooding within coastal watersheds requires advanced hydrologic and coastal storm surge simulation. Such advanced simulation is dependent upon an accurate digital elevation model (DEM) for the optimal topographical representation of the true domain in the discretized model grid (mesh). However, it is not possible to afford mesh resolution as fine as contemporary DEMs, resolved at sub-10 meters, due to the impractical computational expense. Therefore, significant elevation barriers such as roadbeds, levees, railroads, …

Simulation Of Compound Flood Events In Low-Gradient Coastal Watershed, Felix Luis Santiago-Collazo

LSU Doctoral Dissertations

Low-gradient coastal watersheds are susceptible to flooding caused by various flows such as rainfall, tides, and storm surge. Compound flooding occurs when at least two of these mechanisms happen simultaneously or in close succession. Different inundation models, observed data, and/or a combination of these are coupled through varying techniques involving one-way, loosely, tightly, or fully coupled approaches to assess compound flooding. This study presents a one-dimensional (1-D), fully coupled compound inundation model based on the Shallow Water equations. This model approach simultaneously simulates the free water surface variations in the ocean domain (i.e., tide and storm surge modeling), rainfall-runoff in …

Development Of Cracking Resistance Prediction Model Of Long-Term Aged Asphalt Mixtures, Peyman Barghabany

LSU Doctoral Dissertations

With the increasing complexity of asphalt mixture composition, the current volumetric-based Superpave mixture design would not be sufficient to address durability concerns. To address this limitation, performance-based testing is introduced to supplement conventional volumetric mixture design in assessing the cracking resistance of asphalt mixtures. To perform cracking tests, samples need to be aged to represent the most embrittlement case. The current AASHTO standard for asphalt mixture long-term aging (LTA) is a 5-day oven-aging at 85°C. Quality control/assurance practices require samples to be long-term aged prior to a cracking test which is a time-consuming process. Therefore, it would be beneficial to …

Non-Newtonian Model Development For Post-Wildfire Flood Risk Management, Ian Eli Floyd

LSU Doctoral Dissertations

Wildfire effected regions of the western U.S. frequently produce non-Newtonian floods (or floods that have a non-linear relationship between stress and deformation) in response to moderate to severe precipitation events. This research presents the development, evaluation, and demonstration of a post-wildfire hydrodynamic one-dimensional and two-dimensional diffusive wave and shallow-water numerical modeling approach that can be used to predict post-wildfire downstream runout of debris flows and floodplain inundation conditions. While researchers have developed a variety of Non-Newtonian approaches to simulate debris flows and mudflows, there has been very limited application to post-wildfire flooding. This can make it difficult to understand the …

Temperature Gradient Effects On Behavior And Design Of Prestressed Concrete Girder Bridges, Ahmed Saad Elsayed Mohamed Elshoura

LSU Doctoral Dissertations

Temperature variation is an inevitable environmental loading type that affects bridges. Considering temperature effects during structural design is deemed essential for short, medium, and long span bridges. Temperature loading can be categorized into three components; uniform temperature, vertical temperature gradient, and transverse temperature gradient. Temperature variation causes additional movements, stresses, and internal forces that should be considered in the design of bridges. In this study, the temperature effects of vertical and transverse temperature gradients are investigated for continuous prestressed concrete bridges.

Thermal restraint moments induced by vertical temperature gradients on prestrssed concrete bridges are investigated by performing three-dimensional (3D) finite …

Development Of Artificial Intelligence Approach To Nowcasting And Forecasting Vibrio Prevalence In Coastal Waters, Peyman Hosseinzadeh Namadi

LSU Doctoral Dissertations

Vibrio parahaemolyticus (V.p) is an epidemiologically significant pathogen that poses high risks to the human health and shellfish industry, calling for predictive models for management interventions. This study presents an Artificial Intelligence(AI)-based approach to predicting and reducing the risks. The AI-based approach involves the identification of environmental indicators and their optimum variation ranges favoring V.p prevalence, the development of nowcasting and forecasting models for predicting V.p prevalence, and the creation of remote sensing algorithms for mapping concentrations of V.p and its environmental indicators by synergistically combining the Deep Neural Network (DNN) modeling technique, Genetic Programming (GP) method, R …

Data-Driven And Model-Based Methods With Physics-Guided Machine Learning For Damage Identification, Zhiming Zhang

LSU Doctoral Dissertations

Structural health monitoring (SHM) has been widely used for structural damage diagnosis and prognosis of a wide range of civil, mechanical, and aerospace structures. SHM methods are generally divided into two categories: (1) model-based methods; (2) data-driven methods. Compared with data-driven SHM, model-based methods provide an updated physics-based numerical model that can be used for damage prognosis when long-term data is available. However, the performance of model-based methods is susceptible to modeling error in establishing the numerical model, which is usually unavoidable due to model simplification and omission. The major challenge of data-driven SHM methods lies in data insufficiency, e.g., …

Identification Of Top-Down, Bottom-Up, And Cement-Treated Reflective Cracks Using Convolutional Neural Network And Artificial Neural Network, Nirmal Dhakal

LSU Doctoral Dissertations

The objective of this study was to formulate a Convolutional Neural Networks (CNN) model and to develop a decision-making tool using Artificial Neural Networks (ANN) to identify top-down, bottom-up, and cement treated (CT) reflective cracking in in-service flexible pavements. The CNN’s architecture consisted of five convolutional layers with three max-pooling layers and three fully connected layers. Input variables for the ANN model were pavement age, asphalt concrete (AC) thickness, annual average daily traffic (AADT), type of base, crack orientation, and crack location. The ANN network architecture consisted of an input layer of six neurons, a hidden layer of ten neurons, …

Understanding Air Pollutants And Meteorology Interactions Using Chemical Transport Models, Pengfei Wang

LSU Doctoral Dissertations

Air pollution is a worldwide threat to human health and ecosystems, especially in developing countries. After being emitted to the atmosphere, air pollutant concentrations are determined by chemical and physical processes including transport, transformation, and deposition, which are largely affected by meteorological variations. In turn, pollutants such as fine particulate matter (PM_2.5) affect meteorology by impacting solar radiation and cloud condensation processes. Thus, it is important and necessary to understand the interactions between air pollutants and meteorology for better designing effective air pollution control strategies and forecasting weather. In this study, two chemical transport models (CTMs) are applied …

Physical And Biological Factors Controlling The Fate Of Nitrate In A Louisiana Coastal Deltaic Floodplain, Alexandra Christensen

LSU Doctoral Dissertations

The Mississippi River Delta is threatened by a growing pressure to support large human populations in the United States both with food production, navigation systems, and urban development in the Mississippi River Basin. Nitrate-nitrogen load in the Mississippi River, up to 100 Tg N yr^-1 from agricultural and urban runoff, leads to phytoplankton blooms and hypoxia across the Louisiana continental shelf, creating dead zones of low dissolved oxygen threatening a significant commercial fishery. Along the coast and river corridors, floodplain ecosystems have the capacity to retain and remove nitrate. This dissertation explores the role of productive, actively growing coastal …

The Long-Term Outlook Of The Mississippi-Atchafalaya Bifurcation: A Convergence Of Engineering, Economics, And Deltaic Evolution, Thomas Mitchell Andrus

LSU Doctoral Dissertations

The most recent and currently active delta lobe of the Mississippi River (MR) is the Atchafalaya-Wax Lake lobe, which was initiated approximately 400 years ago as a result of MR stream capture by the Atchafalaya River (AR). This capture process accelerated in the early to mid-1900s but further progress was prevented by construction and operation of the Old River Control Structure (ORCS) Complex. Many recent studies indicate that MR system below the ORCS is on a retreating geologic trajectory due to contributing factors such as sea level rise, subsidence, faulting, and declining hydraulic stream power. Diversions along the Lower MR …

Automatic Shoreline Digitization And Mesh Element Sizing For Hydrodynamic Modeling, Henok Kefelegn

LSU Doctoral Dissertations

The first and most critical step in any coastal hydrodynamics and transport process modeling is identifying land-water boundaries. In a coastal wetland, this has always been a challenge due to the complexity of the wetland and lack of efficient methods, calling for efficient and effective methods to extract and digitize the shorelines. While coastline feature extraction has been increasingly researched, its application in hydrodynamic and environmental modeling, without morphological adjustment, remains limited and suboptimal. Further, there has been a paucity of cost-effective, contextually adaptive and high-quality methods to generate meshes, especially for coastal hydrodynamic modeling. This study has developed and …

Safety Assessment Of Road Vehicle In Crosswind Considering Driver Behavior, Jiexuan Hu

LSU Doctoral Dissertations

With expansion of the economy, more and more highway networks extend to coastal areas and mountain valley areas. Vehicles will be exposed to strong crosswinds when driven on these highway roads, especially in hurricane season and in winter in these two different topographic areas. Strong crosswinds threaten the safety of transportation infrastructure and passing vehicles in forms of vehicle accidents that usually result in traffic blockage and driver injury, posing negative effects on economic growth. This dissertation aimed to evaluate the vehicle safety when running through crosswinds in consideration of driver behaviors.

Firstly, the aerodynamic characteristics of road vehicles were …

Investigation Of Subsurface Stratigraphy And Groundwater Dynamics In The Mississippi River Delta, An Li

LSU Doctoral Dissertations

The Mississippi River Delta (MRD) is socioeconomically important to the state of Louisiana and the United States. Various types of land-water system data have been collected in the MRD. However, very few efforts have been made to utilize these datasets in modeling regional stratigraphy and groundwater dynamics in the MRD, especially for the upper 50 m of the depth. In this interval of depth, the Mississippi River and surrounding interdistributary bays intensively interact with the groundwater system. The lack of knowledge in regional stratigraphy and groundwater dynamics hinder an understanding of how hydrogeological setting affects processes such as surface-groundwater interaction, …

Groundwater Management Optimization And Saltwater Intrusion Mitigation Under Uncertainty, Jina Yin

LSU Doctoral Dissertations

Groundwater is valuable to supply fresh water to the public, industries, agriculture, etc. However, excessive pumping has caused groundwater storage degradation, water quality deterioration and saltwater intrusion problems. Reliable groundwater flow and solute transport modeling is needed for sustainable groundwater management and aquifer remediation design. However, challenges exist because of highly complex subsurface environments, computationally intensive groundwater models as well as inevitable uncertainties. The first research goal is to explore conjunctive use of feasible hydraulic control approaches for groundwater management and aquifer remediation. Water budget analysis is conducted to understand how groundwater withdrawals affect water levels. A mixed integer multi-objective …

Performance Study Of Link Slab Continuity In Prestressed Concrete Bridges, Marco Tulio Canales Jr

LSU Doctoral Dissertations

Link slabs in bridges can be a cost-effective solution to increase the service life of bridge structures. The partial continuity condition in link slab bridges, however can be challenging to quantify. In this work link slab performance is studied by means of a parametric study, a long-term Structural Health Monitoring (SHM) System, and a detailed finite-element model.

The parametric study was conducted using mathematical and a two-dimensional (2D) finite element model. The study considers bridge design factors such as number of spans, span length, span length ratio, girder separation, and temperature settings, in conjunction with the corresponding girder and support …

Field Performance And Cost Effectiveness Of Crack Sealing In Flexible And Composite Pavements, Momen Ragab Mousa

LSU Doctoral Dissertations

Surface cracking is one of the major surface distresses in asphalt concrete (AC) pavement, allowing water infiltration through the cracks, causing stripping in asphalt pavement layers, and weakening and deteriorating the base and/or subgrade. Its treatment, therefore, is one of the major activities in pavement preservation for many state DOTs. Among the various treatment methods currently available to preserve AC pavement with existing surface cracking are various forms of crack sealing. Crack sealing is not a common practice to Louisiana highways since the benefit of such treatment appears to be affected by the elevation of the ground water table. Studies …

Numerical Modeling Of Wave Dynamics And Sediment Transport Near The Mississippi Birdfoot Delta And Barataria Estuary, Soroush Sorourian

LSU Doctoral Dissertations

The Barataria Basin is a large estuarine system in Southeastern Louisiana, connected to the Gulf of Mexico through a number of inlets, the most important of which is the Barataria Pass. This research examines, during April-June 2010 including both cold front passage and calm summer-time wind regimes, the wave dynamics in this basin and in its major inlets, morphological evolution near the Barataria Pass, and the budgeting and dispersal of the Mississippi River sediment in the birdfoot delta region. An unstructured grid, terrain following, high resolution coupled FVCOM-SWAVE-SED model is employed and validated in this study. The numerical model results …

Identification And Reduction Of Uncertainties In Watershed-Scale Flow And Water Quality Modeling, Maryam Roostaee

LSU Doctoral Dissertations

This study identified important uncertainties affecting watershed-scale flow and water quality simulations and recommended modeling options for reducing the uncertainties by means of the Hydrological Simulation Program-FORTRAN (HSPF) model. Specifically, parameter-induced uncertainties in HSPF model were estimated along with uncertainties associated with DEM resolutions and sources. National Elevation Dataset (NED) DEMs with original and resampled resolutions of 3.5, 10, 30 and 100m were utilized for manual and automatic delineation of three watersheds with different gradients in HSPF model to identify the effects of DEM resolution, DEM resampling, delineation method and watershed gradient on the simulation of streamflow, nitrate (NO_{3 …}

Coastal Louisiana Landscape And Hurricane Storm Surge Evolution 1850 - 2110, Christopher George Siverd

LSU Doctoral Dissertations

The hurricane storm surge analysis presented in this dissertation examines surge response to changes in the Louisiana coastal landscape and Gulf of Mexico water level from 1850 to 2110. Land to water (L:W) isopleths, lines depicting areas of constant land to water ratio along the modern Louisiana coast, are utilized in the development of a simplified storm surge model that closely reproduces the surge output of a state-of-the-art detailed model. Eleven comparable storm surge models are constructed with each featuring a representation of the Louisiana coastal landscape circa 1850, 1890, 1930, 1970, 1990, 2010, 2030, 2050, 2070, 2090 and 2110. …